DETECTION OF SMALL QUANTITIES OF DOUBLE-STRANDED DNA BY ENHANCED FLUORESCENCE OF SUBSTITUTED ALDEHYDE MODIFIED POLYDEOXYNUCLEOTIDE-ETHIDIUMBROMIDE COMPLEXES

A method for the detection of small amounts of double stranded DNA by a simple incubation procedure involving the reaction of the nucleotide bases in DNA with chloroacetaldehyde is described. Following incubati on, the presence of DNA may be visualized by the orange fluorescence e mitted when ethidium bromide (EtBr) is added. Alternatively, the aldeh yde/DNA mixture may be separated by agarose,gel electrophoresis and in dividual double stranded DNA visualized by exposing the gel to ethidiu m bromide and observing the orange ultraviolet light induced fluoresce nce of the aldehyde modified double stranded ethidium bromide complex (Waring, M.J. (1965) J. Mel. Biol. 13, 269-282). At least a 20-fold in crease in the detection of double stranded DNA is possible by this pro cedure. An important aspect of this method is that the visualization o f single stranded DNA is not enhanced.